HTML <rp> Tag

The <rp> element is used to provide fallback text to be shown by browsers/user agents that don't support ruby annotations.

In the above example, the <rp> element is used so that the browser will display parantheses if it doesn't support ruby annotations. However, the parantheses won't usually be displayed if the browser does support ruby annotations.

About Ruby

Ruby (also spelt rubi) characters are small, annotative glosses that can be placed above or to the right of a Chinese character when writing logographic languages such as Chinese or Japanese to show the pronunciation. Ruby annotations, are usually used as a pronunciation guide for relatively obscure characters.